Corrosion inhibitors in well treating compositions



iron, admiralty metal, steel and ferrous alloys.

CORROSION INHIBITORS IN WELL TREATING COMPOSITIONS Herman Levin, Houston, Tex., assignor, by mesne assignments, to BJ Service, Inc., Long Beach, Calif., a corporafion of Delaware No Drawing. Filed Aug. 13,1956, Ser. No. 603,795 7 20 Claims. (Cl. 252-855) This invention relates to the inhibition of corrosion of metals. More particularly it relates to a composition for use in preventing corrosion of metals such as aluminum, The corrosion inhibitor disclosed herein finds specific application in the prevention of corrosion to well equipment due to brine, hydrogen sulphide, and other acid and corrosive constituents of crude oil, as well as protection of the metal parts during the acidizing and fracturing steps in treating wells with hydrochloric acid compositions to aid in bringing such wells into production.

Heretofore it has been the practice to introduce corrosion inhibitors into oil wells to prevent corrosion of the ferrous metal parts. Certain substances have been successful in preventing corrosion due to weak acids and brine. Aliphatic amines, pyridine, pyrimidine have all been used, but none of these has proven satisfactory against corrosion by strong mineral acids, especially at elevated temperatures and pressure.

It is an object of the present invention to prevent corrosion of metals.

It is a further object of this invention to prevent the corrosion of ferrous metals by strong mineral acids, under normal temperatures and pressures as well as at elevated temperatures and pressure.

It is a still further object of this invention to prevent the corrosion of oil well equipment by the usual corrosive agents obtained from such wells, such as brine, hydrogen sulphide and acid constituents of crude oil.

In addition thereto it is an object of this invention to prevent corrosion during the acidizing treatment of oil wells either to initiate production or to increase production during the life of the well.

The present invention comprises the use of substances prepared by condensing in a liquid phase aliphatic and aromatic aldehydes with ammonia or an ammonia derivative in such a manner as to produce a substituted hydrogenated pyridine compound having a substituted group or groups containing 6 to 20 carbon atoms of the general formula wherein a is an integer from through 7 and b is an integer from 1 to 3, and the sum of a+b is greater than 2 and less than 9, and R represents at least one. substance selected from the group consisting of alkyl and aryl; which substance is attached to the ring.

EXAMPLE 1 1 mol ammonium carbonate 2 mols cinnamaldehyde 4 mols n-butyraldehyde heated at a temperature of 61 to 65 C. (l42150 F.) under atmospheric pressure for 25 minutes. The major portion of the mixed product is 3-benzal-5 -ethy1-2-propyldihydropyridine (2,3).

nited States atent "O 2,955,083 Patented Oct. 4, 1960 In the same manner the following compounds were prepared:

The pyridine ring may be hydrogenated using sodium and alcohol by well known methods.

Compound Chemical name Prepared from- Designation Hydrogenated F. 3,5 dlethy1-2-propyl Compound F. sodium tetrahydroethanol. pyridine. Do 3,5 dietllyl-2-propyl- -..-do Do.

hexahydropyridine.

It has been found that these compounds reduce the corrosion of steel as much as 99.91% when exposed to extreme surface conditions as immersion in 15% by Weight hydrochloric acid solution at a temperature of 300 F. and a pressure of 6,000 p.s.i., the concentration of the inhibitor being 0.15% by weight based on the concentration of the acid.

These compounds have been found to act as corrosion inhibitor where steel is brought into contact with salt solutions in conjunction with sour crude oil containing hydrogen sulphide and certain organic acids as is shown in the following test:

Test] Steel coupons were weighed and placed in test tubes containing 20 ml. of 10% NaCl solution and ml. of sour crude (Levelland Pool). To these tubes, varying amounts of compound F were added, the tubes were placed in an agitating Water bath, and the coupons were agitated for 36 hours at F. and allowed to stand without agitation at room temperature for 84 hours. Agitation and standing periods were alternated. Coupons were removed, cleaned and reweighed, and weight loss aeeaosa i 3 Test 2 Steel coupons were weighed and placed in test tubes containing 95 ml. of 10% (by wt.) NaCl solution and ml. of methanol (a peptizing agent). To these tubes, varying quantities of compound F were added. The tubes were placed in anagitating water bath, and the coupons were agitated for 36 hours at 100 F. and allowed to stand without agitation for 84 hours at room temperature.

Agitation and standing periods were alternated; coupons were removed, cleaned and reweighed, and weight loss and efficiencies calculated.

RESULTS Percent Percent weight efficiency loss 1. 0.107 2. 20 gal. F/1,000 g 0.035 .29 3. gal. F/1,000 gal 0.056 7.66 4. .Sgal. 0.082. 23.36 5. 3 gal. 0.105 1.87 6. 1 gal. 0.094 12.15 7. 0.5 g 0.112 8. .1 g F/1,000 gal 0.128

Metals other than steel are inhibited against corrosion p 'by various types of corrosive agents. Admiralty metal was tested and the corrosion was reduced.

Test 3 A sample of admiralty metal tubing was obtained and test sections werepolisheicleaned, weighed, and placed in test tubes containing 100 ml. of HCl and the required amounts of inhibitor. The tubes were then agitated for two hours at temperatures varying between 206 and 210 F. The tubes were then removed, cleaned and reweighed, and weight loss and efliciencies calculated.

Aluminum was tested toldetermine the effect of the inhibitors when the metal was contacted with 'a 15% hydrochloric acid solution.

Test-4 Coupons were prepared from Alclad 24S aluminum, and weighed. The coupons were placed in beakers and 150 mls. of 15 percent acid were added. The inhibitor was added and the reaction was allowed to proceed for thirty minutes at 100-110 F. Coupons were then removed, cleaned and reweighed, and weight loss and eificiencies calculated.

RESULTS Percent Percent weight efliciency loss 1. Blank (no inhibitor) 70. 501 2. 10 gal.-F/1,000 gal 1.536 a -97. 82

. 1' .Test .5

Coupons were prepared from Alclad 24S aluminum, and weighed. These coupons were then placed in beakers containing 150 ml. of 15% hydrochloric acid and varying amounts of'compound F,-and allowed tostand Inthis test RESULTS Percent Percent weight efliciency loss 1. Blank (no inhibitor) 0. 268 2. 10 gal. F/1,000 gaL- 0. 181 32. 46 3. 5 gal. F/1,000 gal- 0. 190 29.10 4. 3 gal. F/1,000 gal- 0.159 40. 67 6. 1 gal. F/1,000gal- 0. 19,5 27. 24

Percent efilciency Percent weight loss The comparative effectiveness of the several 'dihydropyridine compounds are set forth in the following tests to determine their eifectivenessto preventcorrosion of steel by a "15% 'hydroch'loric acid solution.

7 1 Test 6 The data in this section consists principally in evaluating the anti-corrosion properties of several substituted dihydropyridine compounds. The tests were performed 'in 15% hydrochloric acid .0]: coupons of SAE 1026 steel. Tests were conducted at 100-101 F. and 208210 F. for periods of five hours and one hour, respectively. Methanol or isopropanol was used as a peptizing agent with compounds exhibiting low'solubility in 15 HCl.

TESTS OONDUCTED'A'I 20s210 F. FOR ONE HOUR Percent efliciency at different TESTS CONDUCTED AT.100 F. FOR FIVE HOURS Gom- .005 .01 .015 .03 .05 .10 .15 .20 pound wt. wt. wt. wt. wt. wt. wt. wt.

Per- Per- Per- Per- Per- Pcr- Per- Percent ce-nt cent cent cent cent cent cent 69. 50 82. 93. 98 95. 17 96. 44 97. 56 98. 25 98.00 90. 36 99. 53 99. 93.25 98.58 98. 96 99. 23 99.27

The tetra-hydro and hexa-hydro compounds referred to above show their eifectiveness to prevent the corrosion of steel by a 15% hydrochloric acid solution'as set forth in the following tests:

T est 7 Percent Percent weight efliciency loss 1. Blank 35. 047 2. 10 gahhydrogenated F (13.1. 482 F536 F.) /1,oo0 .887 97. 47 p 3. 5 gal. hydrogenated F (3.1. 482 F530 F.) i /1,000 881 97. 49

Test 8 Percent Percent Weight efiieiency loss 1. 093 97. 22 3. 10 gal. hydrogenated F (13.1 345 419 F.

1 1. 139 97. 10 4. v10 gal. hydrogenated F (B.P. 419568 FJ/ .658 93.32 5. 10-ga1. hydrogenated F (B.P. 568581 F.)/

if,v Test 9 THE TESTS OF CORROSION INHIBITOR COMPOUNDS A, B, D, E AND F IN 15% SULFURIC ACID Sulfuric acid was used as a corrosive agent to determine the efiectiveness of these inhibitors against sulfuric acid in pickling and in industrial cleaning processes. Steel coupons were weighed and placed in test tubes containing 100 ml. of 15% by weight sulfuric acid and 10 ml. of isopropyl alcohol or a mixture of isopropyl alcohol and inhibitor totaling 10 ml. in volume. The tubes were placed in an agitating water bath and coupons were agitated for two hours at 160 F. At the end of the test period coupons were cleaned, dried, and weighed with the following results:

Percent Percent weight etliclency loss Compound A:

Blank 25. 902

2 gal. A/l,000 gal. 15% H 8 04 0. 682 97. 37

5 gal. A/l,000 gal. 15% H28 04... 0. 759 97. 07

gal. A 1,000 gal. H2804 0. 995 96. 16 Compound Blank 27. 169

2 gal. D/l,000 gal. 1. 603 94.18

5 gal. D/l,000 gal. 1. 230 95. 53

10 gal. D/l,000 gal. 15% HzSO 1.178 95. 72 Com ound E:

bank" 29. 225

2 gal. E/1,000 gal. 15% H1804 1.071 96.34

5 gal. E/1,000 gal. 15% H28 04... l. 847 95. 39

10 gal. E/l,000 gal. 15% H 804 1. 473 94. 96 Compound F:

Blank 29. 225

2 gal. F/1,000 gal. 15% H1801 1. 887 93. 54

5 gal. F/1,000 gal. 15% E 8 04. 1. 350 95. 38

10 gal. Lil/1,000 gal. 15% HzSO; 1.334 95. 44

Test 10 TEST OF INHIBITOR COMPOUNDS A, B, D, E AND F IN 15% HYDROCHLORIC ACID This test was run similar to Test 9 only using hydrochloric instead of sulfuric acid to demonstrate the use of these corrosion inhibitors in pickling of various metals or in industrial cleaning operations on heat exchangers, etc.

Steel coupons were weighed and placed in test tubes containing 100 ml. of 15% by weight hydrochloric acid and 10 ml. of isopropyl alcohol or a mixture of isopropyl alcohol and inhibitor totaling 10 ml. in volume. The tubes were placed in an agitating water bath and the reaction was allowed to proceed for a period of 1 hour at a temperature of 208-'2l0 F.

Percent Percent weight efilolency loss Compound A:

Blank 32.082 2 gal. A/1,000 gal. 15% E01 188 99. 41 5 gal. A/1,000 gal. 15% HOL- 280 99. 13 10 gal. A/l,000 gal. 15% HO] 374 98.83 Compound B:

Blank 30. 840 2 gal. B/l,000 gal. 15% HCI... 174 99. 44 5 gal. 3 1,000 gal. 15% B01 166 99. 46 10 gal. B/l,000 gal. 15% HO 2. 41 99. 22 Compound D:

111 36. 248 2 gal. D l,000 gal. 15% E01 251 99. 31 5 gal. D;1,000 gal. 15% HCl 383 98.94 10 gal. D l,000 gal. 15% E01 437 98. 79 Compound E:

Blank 32.242 18. 239 43. 43 1. 150 96. 43 932 97. 11

Bhnk 34. 466 2 gal. F/1,000 gal. 15% HCl 13. 130 61 90 5 gal. F/l,000 gal. 15% E01 4. 538 86. 83 10 gal. F/1,000 gal. 15% HC .724 97. 90

Test 11 CAUSTIC CORROSION OF ALUMINUM Coupons of Alclad 24S aluminum were weighed and placed in test tubes containing ml. of 15% sodium hydroxide solution to which had been added alcoholic solutions of the inhibitors. Test temperature was approximately 210" F. and test time 10 minutes. The fol lowing results were obtained:

Percent Percent weight elficiency loss Blank 18. 351 0 5 gal. per thousand Compound A 12.303 32. 96 5 gal. per thousand Compound B-.- 12. 754 30. 50 5 gaLper thousand Compound D 12.098 34.07 5 gal. per thousand Compound E..- 13.087 28. 69 5 gal. per thousand Compound F 9. 444 48. 54

Test 12 Percent efiiciency Percent Weight loss The solubility of this new group of corrosion inhibitors in water, salt and acid solutions is very low. It has been found possible to fully peptize these new inhibitors in polar solutions by the use of appropriate cosolvents, such as methanol, acetone, ethyl alcohol, isopropyl alcohol, methyl ethyl ketone and others of similar structure. The inhibitor is first dissolved in the cosolvent so as to give about a 20% solution. This solution is added to the liquid to be inhibited in such quantity as to yield the required concentration of inhibitor necessary for satisfactory operation.

This new group of corrosion inhibitors may be used to prevent corrosion of metals by the usual corrosion agents and in addition thereto may also prevent the corrosion of metals by strong inorganic acids or alkalis. They find wide use in the oil industry, particularly in the acidizing of oil wells by means of hydrochloric acid compositions which is a common step in the treatment of oil wells to bring them into production and also may be applied to old wells that have ceased to produce because corrosion of the casing and the attached Christmas tree as well as the pump equipment by the acid used is a serious factor in the treatment of these wells. This invention enables the corrosion to be reduced by 99%.

These corrosion inhibitors also find extensive use in pickling and in industrial cleaning wherein strong acids and alkalis are used. In particular, the reduction of corrosion of aluminum by strong alkalis allows the use of this metal in contact with these materials for the first time.

This application is a continuation-in-part of my copending application Serial No. 425,326, filed April 23, 1954, now abandoned.

Many advantages in the use of this-class of compound 7 will be apparent to one skilled in the art. The above examples are given for illustrative purposes only and do not limit this invention, which is only limited by the scope of'the' claims hereto attached.

What is claimed is: l. A well treating composition comprising an aqueous hydrochloric acid solution anda corrosion inhibitor comprising a derivative of a hydrogenated pyridine of the formula type wherein a is an integer from through and b is an integer from 1 to 3 and the sum of a+b is greater than 2 and less than 7 and R represents at'least one substance selected from the group consisting of alkyl and aryl; which substance is' attached to the ring.

2. The well treating composition of claim 1, wherein the total substance selectedfrorn the group consisting of alkyl and aryl contains from 6 to 20 carbon atoms.

3. The well treating composition of claim 1, wherein the total substance from the group consisting of alkyl and aryl contains carbon atoms.

4. A process for the prevention of corrosion by aqueous acid well constituents of metals selected from the group consisting of ferrous metals, aluminum, and admiralty metal in an oil well comprising the steps of introducing into such Well in an aqueous medium a substituted hydrogenated pyridine of the formula type wherein a is an integer from. 0 through five and b is an integer from 1 to 3 and the sum of a-l-b is greater than 2 and less than 7 and R represents at least one substance selected from the group consisting of alkyl and aryl; which substance is attachedtothe ring. p 5. The process of claim 4, wherein the corrosion inhibitor is introduced into the aqueous medium in conjunction with an oxygenated organic solvent as a peptizing a cut.

6. A process for the prevention of corrosion by aqueous acid well constituents of metals selected from the group consisting of ferrous metals, aluminum, and admiralty metal in an oil well comprising the steps of introducing into such well in an aqueous medium a dihydropyridinc having at least one side chain thereon, said side chain selected from the group consisting of alkyl and aryl containing from 6 to 20 carbon atoms;

7. A process for the prevention of corrosion by aqueous acid well constituents of metals selected from the group consisting of ferrous metals, aluminum, and admiralty metal in an oil well comprising the steps of introducing into such Well in an aqueous medium a tetrahydropyridine having at least one side chain thereon, said side chain selected from the group consisting of alkyl and aryl containing from 6 to 20 carbon atoms.

8. A process for the prevention of corrosion by aqueous acid well constituents of metals selected from the group consisting of ferrous metals, aluminum, and admiralty metal in an oil well comprising the steps of introducing into such well in an aqueous medium a Z-propyl hexahy- 'dropyridine. 9. A process for the prevention of corrosion of metals selected from the group consisting of ferrous metals, aluminum and admiralty metal in an oil well when exposed to a hydrochloric acid solution, comprising the steps of incorporating in a corrosive oil well treating fluid a small quantity of 3,5-diethyl-2-propyl-dihydropyritiine- (213).,

10. A process for the prevention of corrosion by aqueous acid well constituents of metals selected from the group consisting of ferrous metals, aluminum, and admiralty metal in an oil well comprising the steps of introducing into such well in an aqueous medium 3.,5-diethyl-2-propyl dihydropyridine-(Zfi).

11. A process for the preventionof corrosion by aqueous acid well constituents of metals selected; fromthe group '8 consisting of ferrous metals, aluminum, and admirality metal in an oil well. comprising the steps of introducing into such well in anaqueous. medium I3-.benzal-2-methyldihydropyridine-(L'a). y,

12. A process forthe'jpreventionof corrosion .by aqueous acid Well constituents of metals selected from the group consisting of ferrous metals, aluminum, and admiralty netalin-an oil'well comprising the steps of introducing into such well-in an; aqueous medium 3'-benzal -2-propenyl- Y- Y PY d JB) 13. A process for-the prevention of corrosion by aqueous acid wellconstituentsof metals selected from the group consisting- 0f ferrous metals, aluminum, and admirality metal in an oil-wel1- comprising the steps of introducing into such well in an aqueous medium -3-benzal-2-pentadienyl-( 1,3 -dihydropyridine-( 2,3)

14. A process for the prevention of corrosion by aqueous acid well constituents of metals selected from the group consisting of ferrous metals, aluminum and admiralty metal in an oil well comprising the steps of introducing into such Well in an aqueous medium 3-benzal-5-ethyl-2- propyl-dihydropyridine-( 2,3

15. A process for theprevention of corrosion by aqueous acid Well constituents of metalsselected from the group consisting of ferrous metals, aluminum and admiralty metal in an oil Well'comprising the steps of introducing into such well in an aqueous medium 5-amyl-3-ethyl-2- 'propyl-dihydropyridine-i 2 ,3

16. A process for the prevention of corrosion of ferrous metals by a hydrochloric acid solution comprising the steps of introducing into said solution a dihydropyridinc having at least one side chain thereon selected from the group consisting of alkyl and-aryl and containing from 6 to 20 carbon atoms, then: contacting said metal with said solution.

17. A process for the prevention of corrosion of admiralty metal by a hydrochloric acid solution comprising the steps of introducing into said solution a dihydropyridine having at least one side chain thereon selected from the group consisting of alkyl and aryl and containing from 6 to 20 carbon atoms, then contacting said metal with said solution.

v18. A process for the prevention of corrosion of aluminum by a, hydrochloric acid solution comprising the steps of introducing into said solution dihydropyridine having at least one side chain thereon selected from the group consisting of alkyl and aryl and containing from 6 to 20 carbon atoms, then contacting said metal with said solution.

19. A process for the prevention of corrosion of ferrous metals by a sulfuric acid solution comprising the steps of introducing into said solution a dihydropyridine havirig at least one side chain thereon selected from the group consisting of alkyl and aryl and containing from 6 to 20 carbon atoms, then contacting said metal with said solution. a

20. A process for the prevention of corrosion of aluminum by a sodium hydroxide solution comprising the steps of introducing into said solution a dihydropyridine having at least one side chain thereon selected from the group "2,388,059 Herlocker Oct. 30, 1945 2,472,400 Bond et al Tune 7, 1949 2,493,462 Menaul Ian. 3, 1950 2,694,001 Hayes et al. Nov. 9, 1954 2,698,295 Cardwell' et al. Dec. 28, 1954 2,748,140 Schmidle et al May 29, 1956 2,750,385 Schmidle et al June 12, 1956 2,776,263 Hiskey et a1. Jan. 1, 1957 2,784,192 Schmi'dle et al Mar. 5, 1957 2,807,585, Gardner et a1. Sept. 24, 1957 UNrrEn STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2 955 083 October 4 1960 Herman Levin hat error appears in the above numbered pat It is hereby certified t that the said Letters Patent should read as ent requiring correction and corrected below.

Column 5 second table under the heading "Percent weight loss line 8 thereof for "2.41" read 241 o Signed and sealed this 1st day of October 1963.

(SEAL) Attest:

ERNEST Wa SWIDER DAVID L LADD Attesting ()fficer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION I Patent No, 2955,0553 October 1 1960 Herman Levin.

It is hereby certified that error appears in the above numbered pat-E- ent requiring correction and that the said Letters Patent should read as corrected below.

Column 5 second table under the heading "Percent" weight 1055"" line 8 thereof for "2,41" read 0241 Signed and seeled this 1 st day of October 1963.,

(SEAL) Attest:

ERNEST wt, SWIDER v i DAVIDL LADD Attesting Officer Commissioner of Patents 

1. A WELL TREATING COMPOSITION COMPRISING AN AQUEOUS HYDROCHLORIC ACID SOLUTION AND A CORROSION INHIBITOR COMPRISING A DERIVATIVE OF A HYDROGENATED PYRIDINE OF THE FORMULA TYPE 